Stream-lined sword carrier for subaqueous sound apparatus



Nom 26, 1935.

STREAM LINED SWORD CARRIER FOR SUBAQUEOUS SOUND APPARATUS H. HEcH'r2,022,038

Filed Nov. 4,A 1952 2 sheets-sheet 1 Nov. 26, 1935. ||l HEHT 2,022,038

STREAM LINED SWORD CARRIER FOR SUBAQUEOUS SOUND APPARATUS Filed Nov. 4,1932 2 Sheets-Sheet 2 su al Patented Nov. 26, 1935 ITED STATSSTREAM-LINEE) SWORD CARRIER FOR SUBQUEOUS SUND APPARATUS Heinrich Hecht,Kiel, Germany, assignor to Electroacustic Gesellschaft mit beschrnkterHaftung, Kiel, Germany Application November 4, 1932, Serial No. 641,166In Germany November 27, 1931' 7 Claims.

In order to transmit sound signals from ships well and uniformly in alldirections under water and to receive sound signals well from alldirections with Vertical groups of transmitting-receiving apparatus,groups of this type of apparatus have already been built into aprotrudable carrier of streamlined cross-section. Such a carrier isrigidly guided when protruded, so that its horizontal longitudinal axisextendsparallel l0 to the longitudinal axis of the ship. On turning theship, in which case the ship, as is well known, undergoes a considerablelateral displacement, such rigidly guided apparatus is pulled throughthe water at a high speed at considerable inclination of its horizontallongitudinal axis to the prevailing travelling direction up to 15 andmust therefore have great transverse strength and therefore a verycompact form. This compactness of form results in a ratio of thehorizontal longitudinal axis of the cross-section of the lstreamlinedbody to its thickness so unfavorable that eddy-free streamlined bodiescan be designed only for speeds up to 13-15 knots. A more extension ofthe horizontal longitudinal axis of the streamlined body is notpracticable, because thereby the size of the side-surface of the bodyand thus the stress on being pulled laterally through the currentsimultaneously increase and this eifect must be compensated for again bya corresponding increase in the thickness of the body. With protrudableapparatus which are rigidly guided or rigid in themselves, therefore,the problem of constructing a streamlined body of acoustically perfect,eddy-free qualtities for speeds of more than about 15 knots cannot besolved.

The invention solves this problem by making the streamlined carrier bodyrotatable as a whole on an axis longitudinal of the carrier or, atleast,

by making its rear part rotatable, so that when the ship travels in acurve, the body adjusts itself to the prevailing direction of flowoccurring at the body due to the relative movement between the g vesseland the water. Itis thereby relieved of the task of having to endureconsiderable lateral' stresses when pulled partly in a transversedirection, and the ratio of the length of its horizontal longitudinalaxis to its thickness can now be dimensioned to attain good andeddy-free streamline qualtities accorcng to the requirements dictated bythe maximum speed required.

For the speeds in modern high-speed ships of more than 25 knots, a ratioof the carrier thickness to the length of the longitudinal axis of its553 vcross-sectional. area is. necessary which must not substantiallyexceed the value 1:8. Calculations and experiments have shown that withsuch dimensions at the said speeds, a cross-sectional shape which isparaboloidal in front and runs to a point at the rear is obtainablewherein, on mov- 5 ing the body with its cross-sectional longitudinalaxis parallel to the relative water ow direction, or prevailingdirection of travel, or at quite small angles (2n-3) to the latter,drops in pressure alongthe side surfaces, which lead to acousti- 10cally disturbing eddies and detachments, do not arise.

Carriers having a cross-section of streamline character with a ratio ofthe thickness to the cross-sectional longitudinal axis of about 1:4 tol5 1:6 have hitherto already been constructed These carriers are rigidlyxed to the ship and therefore, owing to the considerable stresses atsharp turns of the ship, it was not possible t0 make the horizontalcross-Sections of the carriers 20 smaller. With an arrangement such asconstitutes the subject off the invention, the carrier always adjustsitself to the prevailing direction of travel and thus is not subjectedin practice to any lateral stresses during turning. Therefore a sub- 25stantially thinner prolile, say, at the ratio 1:8, 1:9 or still thinnercan be chosen.

Several forms of construction of the invention are disclosed in thedrawings in which Fig. 1 shows an assembly of a complete pro- 30trudable apparatus according to the invention,

Fig. la is a front elevation of the upper carrier portion which iscontained in the basev 2,

Fig. 2 is a view of the carrier apparatus from below, 35

Fig. 3 a transverse section through an apparatus carrier according tothe invention,

Fig. 4 a diagram of the distribution of pressure at the surfaces of thecarrier, and

Fig. 5 a different form of construction of the 40 carrier.

In Fig. l, l denotes a cylindrical casing mounted on the hull 3 throughthe agency of a baseA part 2 over a circular hull opening 4. Movablyarranged in the casing is a piston 5 which can 45 be lifted and loweredby way of a spindle 6 and gear train l, la through a motor 8. The pistonhas a hollow boss 9 in which a stud lll is rotatably mounted. This studis fixed to or integral with, the upper end lla of streamlined carrier Hwhich is thickened at the top portion located in base 2,`to permit theuse "of a sufciently strongstud (Fig. la). This carrierfcontains in itslower portion the sound apparatus (transmitters and/or receivers). Thesound apparatus 551 are assumed to be electromagnetic devices which areconnected by the lines I3, lli of the cable i5 to the exciting generatori5 or the amplifier Il and the telephone I3. The cable is arranged inthe casing i in the form of a spiral and on moving the piston 5 thespiral is compressed to a correspnding extent. The carrier il can adjustitself in the direction of travel about the longitudinal axis of thestud l5. prevent undesired oscillating movements, a frictional dampingdevice i9 is provided (see also Fig. 2), and to relieve the load on thestud lil the carrier is provided at its top rear end with a rollerbearing 20.

In Fig. 2, the opening 4 in the ships hull is seen from below as acircular opening. The centre of rotation of the carrier is' about at 2i.It is seen that the circle of rotation of the carrier intersects thecircle of the hull opening atV theV points 22, 23. In order that thecarrier may not go beyond these points, stops 24, 25 are provided. Asound apparatus (transmitter and/or receiver) is indicated here at i2.

In Fig. 3 is shown a transverse section through the carrier with anelectromagnetic sound transmitter and/or receiver, wherein 2l, 2l denotethe body of the carrier, 28 the casing of the transmitter and/orreceiver with the diaphragms 29, 30. The electromagnet halves 3l, 32between which the exciting coil 33 is mounted are xed to the diaphragms.

As has already. been mentioned in the preamble, it has become possibleby this arrangement of the carrier to reduce its lateral stresses to avery great extent. Therefore it can be given an unusually thin form,which ensures the qualities of an excellent streamlined body even athigh speeds of travel (25-30 knots), It has been found that the ratio ofthickness to horizontal length of the streamlined body for theabove-mentioned ranges of travel must not exceed the value 1:3. In Fig.4 the distribution of pressure on the surface of such a body forinclination angles between 0 and 3 (horizontal angle of carrierinclination with respect to the direction of travel) is diagrammaticallyillustrated. The pressure fos produced by the damming-up of the water isinfluenced by conditions expressed by the formula ps-Z-a-c in which g isthe earth acceleration, v the travelling speed, both in meters persecond, and c a factor, whose value depends upon the Apoint at the swordprofile at which the pressure is observed. This factor is derived forthe different angles of sword inclination to the travel direction from agroup of curves empirically obtained for each sword profile. Forinstance, for the aforedescribed profile shown in Fig. 3, the curvesrepresented in Fig. l prevail. The middle curve is for the inclinationangle 0, the lower curve for the angle 3 and for the high pressure sideof the sword, and the upper curve for the angle 3 and for the lowpressure side. The ordinates ps represent the pressure values, derivedfrom the above formula which must be added to or subtracted from thenormal damming-up pressure prevailing at the several points of the swordprole. The abscissae represent the corresponding points on the prole Inorder to line, which latter is inserted on the abscissa axis in dottedlines. This value V2 -c= ps has the character of a water column (inmeters) which corresponds (in height with the hydrostatic pressuresprevailing at the several points of the profile. For a speed of forinstance 15 German knots per hour (the speed of 1 German knot: 10 .5144m/sec.) the ordinary damming-up pressure v 2 l 7.72 s9.292li-approximate y ETS- V9.6

a water column 3 meters in height in round g- 15 ures, or approximately0.3 atmospheres. This value must be added with positive or negativesign, as the case may be, to the static pressure on the surface of thesword body. For instance, it appears from the graph in Fig. 4 that for asword 20 with a profile, there indicated, and at a speed of 15 knots,and a sword depth of 10 meters, and at an inclination angle 0, theabsolute pressure against the leading edge equals 2 kg/cm2-i-03 kg/cm21, which corresponds with the formula 25 wherein P represents the staticpressure. Thus the total damming-up pressure at 'this point 30 amountsto 2.3 kg/cm2. At an inclination angle of 0 at 10 meters` depth and aspeed of 15 knots (a practical case for very large vessels) the absolutepressure does not drop below 1.5 atmospheres at any point.

For the dynamic stresses exerted against the surface of the sword it isthus always important to ascertain the absolute damming-up pressurewhich is produced by the speed of travel, while for the avoidance ofeddies, which are particu- 40 larly detrimental for acoustic effects(eddy noises, air separation noises) the relative distribution of theabsolute pressure along the surface of the sword is of importance. Forinstance, abrupt changes in pressure and negative pressures tend 45 tolead to air separation and eddy formation, for example at the point p inthe curve for 3 at the negative pressure side. In the present case andunder the assumed conditions a pressure of 2*0.3 1:1.7 atmospheresprevails,which is still 50 a sufciently high pressure. However, eventhis case should be avoided as much as possible, because theconsiderable pressure increase at the right of point p may, in certaincircumstances, already lead to detachments and eddy formations 55 andcare should be taken that the adjustment of the apparatus to thedirection of travel is elected as completely as possible.

In order that the adjustment of the carrier to the real direction offlow may take place auto- 60 matically, the carrier must, of course, bein dynamically Istable equilibrium during travel. For this purpose, itis necessary that the vertical axis of rotation about which the rotationof the carrier takes place should be preferably in the 55 frontthird-part of the carrier in order to obtain sucient stability intravel.

A somewhat less complete solutionof the problem is shown in section inFig. 5 by way of suggestion. I-Iere, not the whole carrier body rotates70 to follow the line of flow but only the rear part 40 after thefashion of an Oertz rudder; this part 40 may be hinged on a verticalaxis, for instance, at 41 to the forward half of the carrier 42. At 12is shown again the actual sound apparatus.

The profile shape must, of course, be adapted to the speed at which theapparatus is pulled through the water. At still higher speeds of travelof 35-40 knots, for instance, still thinner profiles must be used. Themanner of damping may, of course, be different from that shown at 19 inFig. 1. This primitive damping is only shown for the sake of simplicityin the drawings.

The manner of movement of the carrier may also be substantiallydifferent from that illustrated, the present showing being merely anillustration of one of the many ways in which the present inventionv maybe reduced to practice. Any suitable means may be employed for turningthe carrier, or part of it in the direction of flow.

Tvvo main features result as the essential advantages of the invention,rstly the possibility of providing only a thin streamlined form of thecarrier itself, and secondly its adjustability to the direction of flowprevailing at the time at the carrier.

I claim:-

1. An arrangement on a vessel forsubmarine sound communication,comprising in combination with the hull of the vessel an elongatedcarrier protruding through the hull at least during sound communicationand containing the submarine sound apparatus, said carrier. having across-sectional area of streamline shape, at least a part of saidcarrier being freely rotatable through a desired angle on an axis inparallel to the longitudinal carrier axis, to permit the adjustment ofthe freely rotatable part of said carrier to the flow direction of theWater surrounding the carrier,

2. An arrangement on a vessel for submarine sound communication,comprising in combination With the hull of the vessel an elongatedcarrier protruding through the hull at least during sound communicationand containing the submarine sound apparatus, said carrier having across-sectional area of streamline shape, at least a part of saidcarrier being freely rotatable through a desired angle on an axis inparallel to the longitudinal carrier axis, to permit the adjustment ofthe freely rotatable part ofv said carrier to the ilovv direction of theWater surrounding the carrier, the ratio of the thickness of saidcarrier to the length of the longitudinal axis of its cross-sectionalarea being not more than 1:8.

3. An arrangement on a vessel for submarine sound communication,comprising in combination with the hull of the vessel an elongatedcarrier protruding through the hull at least during sound communicationand containing the submarine sound apparatus, said carrier having across-sectional area of streamline shape, and means for freely rotatablysupporting said carrier from Within said hull on an axis in parallel tothe longitudinal carrier axis, to permit thefree adjustment of saidcarrier to the flow direction of the Water surrounding the carrier.

4. An arrangement on a vessel for submarine sound communication,comprising in combination with the hull of the vessel an elongatedcarrier protruding through the hull at least during' sound communicationand containing the submarine sound apparatus, said carrier having across-sectional area of streamline shape, and means for freely rotatablysupporting said carrier from within said hull on an axis in parallel tothe longitudinal carrier axis and removed from the leading carrier edgenot more than one-third of the length of the cross=seetional carrierarea, to permit said carrier to freely follow the flovv direction of theWater surrounding the carrier.

5. An arrangement on a vessel for submarine sound communication,comprising in combination With the hull of the vessel an elongatedcarrier protruding through the hull at least during sound communicationand containing the submarine sound apparatus, said carrier having acrosssectional area of streamline shape, and means for freely rotatablysupporting said carrier from Within said hull on an axis in parallel tothe longitudinal carrier axis and removed from the leading carrier edgenot more than one-third of the length of the cross-sectional carrierarea, to permit said carrier to freely follow the oW direction of theWater surrounding the carrier, and means for limiting the angularmovement of said carrier.

6. An arrangement on a vessel for submarine sound communication,comprising in combination with the hull of the vessel an elongatedcarrier protruding through the hull at least during sound communicationand containing the submarine sound apparatus, said carrier having acrosssectional area of streamline shape, and means for freely rotatablysupporting said carrier from Within said hull on an axis in parallel tothe longitudinal carrier axis and removed from the leading carrier edgenot more than one-third of the length of the cross-sectional carrierarea, to permit said carrier` to freely follow the flow direction of theWater surrounding the carrier, and means for damping the angularmovement of said carrier.

'7. An arrangement on a vessel for submarine sound communication,comprising in combination with the hull of the vessel an elongatedcarrier of streamline cross-section protrudable through the hull andcontaining the submarine sound apparatus, a cylinder inside the vesseland a piston movable in said cylinder and serving as a support for theupper end of said carrier, a stud pivoted in said piston and fixed tothe upper carrier end near its leading edge to permit the free rotationof said carrier on an axis extending longitudinally of said carrier nearits leading edge, and permitting the carrier to freely follow the flowdirection of the Water surrounding the carrier, means for limiting theangle of rotation of said carrier, and means for damping its rotarymovements.

HEINRICH HECHT.

